Grain yield improvements by conventional breeding have nearly reached a plateau in crop plants. It is natural then to explore some alternative, non-conventional approaches that could be employed to obtain further yield increases.
Technologic developments continually advance in an effort to address the need to increase plant yield in order to feed the expanding world population. Biotechnology is playing an increasingly important role in this effort by providing, for example, plants having increased resistance to drought and insect infestation. For many plants such as corn, rice and soybean, seed provides the source of food products, including grain and can be eaten directly or processed into flour, milk products and the like. For other plants, edible seeds, roots, stems, leaves, bulbs and tubers provide a source of vegetables. Fruits, which are the ripened reproductive body of plants, also are an important food source.
Because many foods are derived, either directly or indirectly, as a result of plant flowering, methods for increasing flowering efficiency and numbers of flowers produced of plants can result in increased yield. Further, while providing a means to increase yield of crop plants, such tools also can be useful in the ornamental plant industry, providing, for example, a means to increase the number and/or size of flowers produced by a plant.
Nearly all crops may be benefited by the manipulation of growth and development characteristics. As such, mutations in the reception and signal transduction of gibberellins leading to dwarf-like plants have been described as advantageous in many crop plants (U.S. Pat. No. 6,307,126; U.S. Pat. No. 6,762,348; U.S. Pat. No. 6,830,930; U.S. Pat. No. 6,794,560). This was especially true in high-yielding, semi-dwarf wheat varieties where the reduced plant stature was most advantageous in increasing grain production per plant and superior straw strength. The shorter, stronger straw greatly reduces the losses resulting from lodging or flattening of the standing wheat plants by rain and high winds. In addition a concomitant increase in harvest index was evident shifting more photoassimilates from vegetative growth components to the grain.
Methods and compositions are needed in the art which can employ such sequences to modulate harvest index and yield in plants.